Philip,
No doubt that diversification is a brilliant strategy to survive.
Very few operators own patents to technology. The technology in the telecom space is largely owned by equipment vendors. Safaricom diversified from Voice into data, but did not need to develop their own 3G/LTE technology to do that. They simply deployed that technology that has been developed by other people.
In order to survive telecom companies need to leverage the different technologies available, and deliver these as products to the consumers.
If there is a disruptive idea like mpesa, then this can be developed internally - or in collaboration with third parties. At one point though, it would probably be easier for the telco to license/buy that technology from a third party than continue developing it.
Also note that nowadays, telecom vendors also have mobile money products that could possibly deliver same functionality as Mpesa or even more enhanced features.
Regards,
Tito